Micromechanical Modeling Using Low Magnitude Mechanical Stimulation

Overview

The response to a daily 10 minute session of low-magnitude mechanical stimulation (LMMS) on bone in 100 postmenopausal women ages 45-65 years will be evaluated at baseline and 12 months using high-resolution magnetic resonance (MR) imaging. Subjects will be assigned to an active platform that produces vibrations or to a placebo platform that produces no vibrations. The investigators propose to evaluate the hypothesis that LMMS applied to postmenopausal women ages 45-65 improves the mechanical integrity of bone while lowering marrow adiposity. 1. The investigators will optimize an integrated imaging protocol for high-resolution structural MR imaging of the distal tibia and spectroscopic imaging-based quantification of bone marrow composition in the lumbar vertebrae. 2. The investigators will further develop and validate micro-finite-element (FE) analysis for quantitative assessment of trabecular and cortical bone stiffness and failure load from high-resolution MR images of the distal tibia. 3. The investigators will apply the methodology of Aims 1 and 2 (above) in a double-blinded, randomized, placebo-controlled study to a cohort of 100 healthy postmenopausal women in the age range of 45-65 years, studied at baseline and 12 months after having been subjected to 10 minutes daily of either 30 Hz/0.3g stimulation or placebo treatment, monitored rigorously via electronic feedback.

Weightbearing exercise has an osteogenic effect by reducing bone resorption and enhancing bone formation. During the past several years a number of articles have appeared demonstrating that low-magnitude mechanical stimulation (LMMS) is osteogenic in animals and also in humans. Preclinical studies have also demonstrated an effect of decrease in adiposity. The mechanobiology underlying these phenomena is beginning to emerge in terms of expression of genes stimulated by the action of the vibrations to which osteocytes and adipocytes are subjected. If successful, LMMS treatment, a non-pharmacologic intervention, could prevent bone loss and potentially stimulate bone formation and decreased adipocyte production resulting in increased bone strength and reduced fracture susceptibility in subjects at risk of developing osteoporosis. The proposed project focuses directly on measures of strength by evaluating the therapeutic response in terms of magnetic resonance (MR) image-based micro finite-element (FE) assessment of bone stiffness and failure strength, along with quantifying treatment-induced changes in marrow adiposity, as part of a single, integrated examination, conducted at baseline and 12 months of treatment in a double-blinded, randomized, placebo-controlled study of early postmenopausal women.